Virtually all cellular responses, including growth and differentiation, are stringently controlled by physiological signals in the form of growth factors, hormones, nutrients, and contact with neighbouring cells. These various signals are processed and interpreted by signal transduction mechanisms which ultimately induce the cell to mount an appropriate response. Signalling pathways stimulated by physiological signals involves a network of specific protein-protein interactions which function to transmit the signal to downstream effector molecules that execute the response (32). Thus specific interactions between proteins are critical for signal transduction mechanisms as well as regulation of cellular architecture and responses to physiological signals. Given that specific protein-protein interactions are involved in execution of virtually all cellular functions, technologies which simplify and facilitate detection and analysis of specific protein-protein interactions will be valuable for the discovery, design and testing of drugs that target highly specific biological processes.